1. Field of the Invention
The present invention relates to an information processing system having a main unit, at least one sub-unit controlled by the main unit and a data bus interconnecting at least one sub-unit and the main unit, and more particularly to an information processing system which permits transfer of data in an efficient manner in a system comprising a plurality of units having a number of functions.
2. Related Background Art
In a prior art multi-function system having a plurality of functional blocks, speed-up of data transfer to and from a controller which controls the blocks is done mainly by improving the processing speed of the controller, that is, improving the performance of the built-in CPU.
However, the provision of a high performance CPU to increase the processing speed of the controller leads to an increase in the cost and complexity of the apparatus and also to an increase in power consumption, and hence it cannot be readily adopted.